Skip to content

Didactic Guide: School Market for Primary School - STEM

School market: addition, subtraction and budgeting

Upper primary - 9-11 years - Duration: 2 sessions of 50 min.

Introductory question

How do you know if the money you have is enough and how much change you should get back?

Explanatory summary

This guide will help you create a «flea market» in the classroom. Students will act as buyers and sellers, using play money to practice addition and subtraction in real-life situations. They will learn how to budget, the value of saving, and the importance of making smart buying decisions.

Skills to be developed

  • Cognitive: Application of mathematical operations, problem solving and budget planning.
  • Socioemotional: Decision making, negotiation, assertive communication and empathy.
  • Internships: Money management, organization of a sales stand and exchange rate calculation.

Standards linked: Common Core (Mathematics), UNESCO (Life Skills).

Learning objectives

  1. Solve addition and subtraction problems in buying and selling contexts.
  2. Create and manage a simple budget to make purchases.
  3. Correctly calculate change when paying for products.
  4. Justify purchasing decisions based on budget and needs.

Materials

Economical (Recycled)StandardPro (Digital)
Paper to create tickets, classroom products with handmade price tags, empty containers (boxes, bottles).Toy money, plastic products (fruits, vegetables), small baskets, one basic calculator per team.Toy cash register, complete market set, one tablet per team with a simple point-of-sale application.

Note: Prioritize the use of recyclable materials and ensure that all items are safe for the age of the students.

Step-by-step procedure

  1. Phase 1: Planning and Assembly - Form teams, assign roles (sellers/buyers), create the products with their prices and design the money. Each buyer receives a quote. (50 min)
  2. Phase 2: Market Day! - Start the simulation. Shoppers visit stores to purchase products on their list, within their budget. Salespeople calculate totals and deliver the correct change. (30 min)
  3. Phase 3: Closing and Reflection - As a group, share the experience: Did you find the money? Did you buy everything you needed? Review calculations and discuss the importance of saving and budgeting. (20 min)

Formative evaluation

Reflection questions:

  • How did you decide which products to buy with your budget?
  • What was more difficult: calculating the total or making change?
  • If you had more money next time, what would you do differently?

Evidence to be collected: Completed budget sheets, purchase tickets with the calculations made and direct observation of the teacher during the activity.

Evaluation rubric

CriteriaInitialBasicAdvancedExpert
CalculationRequires constant assistance with addition and subtraction.Perform simple calculations with some errors.Performs calculations correctly most of the time.Calculate totals and changes quickly and without errors.
BudgetSpend money without following a plan.Attempts to follow the budget but exceeds it.Adheres to the allocated budget.Optimize your budget, comparing prices and making strategic decisions.
DecisionsBuy products at random.Choose products, but without justifying your decision.Justify your purchases based on need and budget.Argue their decisions, differentiating between need and desire.

Differentiation

  • Supports: Use calculators, assign prices with round numbers (e.g., $10, $50) and provide guided shopping lists.
  • Extensions: Include 2×1 «offers» or 10% discounts to enter percentages and more complex calculations.
  • Challenges: Ask sales teams to calculate their «profit» at the end of the day or have buyers create a savings plan.

Connections to daily life

  • Finance: Introduces key financial literacy concepts such as spending, saving and budgeting.
  • Values: It allows us to discuss consumerism, the difference between need and want, and the option of «donating» part of the money.
  • Environment: Encourages creativity and sustainability by creating products and money from recycled materials.
Safety and sustainability

Encourage the use of recycled materials for the creation of products and tickets. Ensure that the objects used are safe and do not present a choking hazard when working with younger children. At the end, promote the correct classification of materials for recycling.

Guide generated by Gutenberg AI. Free license for educational purposes.

Link copied to clipboard
' ], { type: 'text/html' }); const url = URL.createObjectURL(blob); const a = document.createElement('a'); a.href = url; a.download = slug + '-guia.html'; document.body.appendChild(a); a.click(); a.remove(); setTimeout(() => URL.revokeObjectURL(url), 5000); } catch(e){ console.error('Error al descargar:', e); alert('No se pudo generar la descarga.'); } });btnShare?.addEventListener('click', async () => { if (!navigator.clipboard) { alert('La función de copiar no está disponible en este navegador.'); return; } try { await navigator.clipboard.writeText(window.location.href); toast?.classList.add('show'); setTimeout(() => toast?.classList.remove('show'), 1800); } catch(e){ console.error('Error al copiar:', e); alert('No se pudo copiar el enlace.'); } }); })();